Blue Banana is a complicated "work of art"! Since I have found a typo in the Manual in the Blue Banana plugin section, I will add Beghetto's summary of how alpha works as he stated below. Thanks too from me for the illustrative video.

On Mon, Apr 1, 2024 at 3:59 AM Igor BEGHETTO via Cin <cin@lists.cinelerra-gg.org> wrote:

What I know, "alpha" slider works with both "Filter Active" and "Mask Selection" checkboxes checked.
The "Filter Active" checkbox enables the options: red, green, blue, hue, saturation, value, fade, alpha.
If "Mask Selection" is not checked "alpha" will not work.

Take a look at the video "Cin_BluBanana-alpha", please:
https://files.fm/u/d3t4uf3kyc

IgorBeg

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